Micro and nano texturing of polymers and other materials to produce
smart surfaces of tuned wetting and reflectivity

Producing smart polymer surfaces by tuning of their
properties is of extreme importance in nanomanufacturing, as well
as microfluidic applications. It is desirable that modern smart
surfaces mimic nature by being self-cleaned (lotus leaf like), antireflective
and transparent etc. Such properties can be given to a surface by
producing tailored dual scale micro / nanotopography, and appropriate
surface chemistry. Their combination can lead to superhydrophobic
or superhydrophilic and / or graded refractive index optical surfaces
with minimal reflection. In this field, we explore plasma processing
as a route for fast and cost-efficient nanofabrication technology.
We are studying a variety of polymeric substrates (PDMS, PMMA, PEEK,
etc.) and silicon with respect to their surface topography modification
upon plasma exposure, and we can obtain superhydrophobic or superhydrophilic
as well as surfaces of controllably defined wetting properties (from
hydrophilic to hydrophobic), depending on the plasma processing
details. We can also tune the transparency.

Etching of silicon in SF6 plasmas produced interesting
nanotexture shown below. Although this nanotexture is small compared
to etched depth (etch rate approximately 4 microns/min) it grows
with time both in height and diameter.